.bttn-stretch
  {bttnBaseStyle}
  {bttnMdSize}
  overflow hidden
  border-width: 0;
  border-radius 0
  background transparent
  color: cWhite;
  letter-spacing: 0
  transition all 0.2s anim_func
  &:after, &:before
    position: absolute;
    left: 0;
    width: 100%;
    height: 1px;
    background: currentColor;
    content: ''
    opacity 0.65
    transition all 0.2s anim_func;
    transform scaleX(0)
  &:after
    top: 0;
  &:before
    bottom: 0;
  &:hover, &:focus
    letter-spacing: 2px;
    opacity 0.9
    transition all 0.3s anim_func
    &:after
      opacity 1
      transition all 0.3s anim_func
      transform scaleX(1)
    &:before
      opacity 1
      transition all 0.3s anim_func
      transform scaleX(1)
  &.bttn-xs
    {bttnXsSize}
  &.bttn-sm
    {bttnSmSize}
  &.bttn-md
    {bttnMdSize}
  &.bttn-lg
    {bttnLgSize}
  &.bttn-default
    color cWhite
  &.bttn-primary
    color cBlue
  &.bttn-warning
    color cYellow
  &.bttn-danger
    color cRedLight
  &.bttn-success
    color cGreen
  &.bttn-royal
    color cPurple